On the Origin of Species

On the Origin of Species Plot Summary

Introduction

In the spring of 1837, a young naturalist sat at his desk in London, opening his first notebook on "the transmutation of species." Charles Darwin had returned from his voyage on the HMS Beagle with observations that would eventually shake the foundations of how humans understood their place in the natural world. Yet he was far from the first to wonder about the origins of life's diversity. For centuries, scholars had puzzled over fossils of extinct creatures, the striking similarities between different animals, and the curious distribution of species across the globe. These mysteries begged for explanation, and the answers would prove more revolutionary than anyone imagined. The story of how natural selection came to be understood is itself an evolutionary tale—one of ideas competing, adapting, and ultimately transforming our view of life on Earth. Through this journey, we'll explore how early naturalists grappled with evidence of species change long before Darwin, how the theory of natural selection emerged and faced fierce resistance, and how modern science has validated and expanded upon Darwin's revolutionary insights. This exploration reveals not just scientific breakthroughs but also how human understanding itself evolves—sometimes gradually, sometimes in revolutionary leaps—as we continue to unravel the magnificent complexity of life's four-billion-year journey.

Chapter 1: Early Theories: Pre-Darwinian Views on Species Change (1750-1850)

The century before Darwin published his revolutionary theory was marked by growing intellectual ferment regarding the nature of species. In the mid-18th century, the prevailing view across Europe was that species were fixed entities, created by God in their present form. This perspective, championed by influential naturalists like Carl Linnaeus, held that species might show minor variations but could not fundamentally change or transform into new species. Linnaeus's famous taxonomic system, introduced in his 1735 work "Systema Naturae," provided a framework for classifying organisms but initially assumed the permanence of species. By the late 18th century, however, cracks began appearing in this edifice of species fixity. The French naturalist Georges-Louis Leclerc, Comte de Buffon, suggested in his massive "Histoire Naturelle" that related species might have shared ancestors, and that environmental factors could cause species to degenerate from their original forms. Though Buffon vacillated in his views, his writings introduced the radical notion that species might change over time. Meanwhile, Erasmus Darwin (Charles's grandfather) proposed in his "Zoonomia" (1794-1796) that life might have descended from a common ancestor, with species adapting to their environments over generations. The most comprehensive pre-Darwinian evolutionary theory came from Jean-Baptiste Lamarck, who in 1809 published his "Philosophie Zoologique." Lamarck proposed that organisms could acquire traits during their lifetimes and pass these acquired characteristics to their offspring. His famous example involved giraffes stretching their necks to reach higher leaves, with this stretching supposedly causing longer necks in their descendants. While this mechanism of inheritance was later disproven, Lamarck deserves credit for being the first to propose a coherent theory of evolution that included both the transformation of species and a mechanism to explain it. The emerging science of geology provided crucial context for these early evolutionary ideas. James Hutton's theory of uniformitarianism suggested that Earth was shaped by slow, gradual processes still operating today, implying an Earth far older than the biblical chronology allowed. Charles Lyell expanded on these ideas in his influential "Principles of Geology" (1830-1833), which the young Darwin read during his voyage on the Beagle. Lyell demonstrated that geological processes required vast time periods, providing the temporal framework necessary for gradual evolutionary change. By the 1830s and 1840s, the intellectual stage was set for a more comprehensive theory of evolution. Naturalists had accumulated extensive evidence of extinct species through fossil discoveries, raising questions about why these creatures had disappeared and how they related to modern forms. Comparative anatomists like Georges Cuvier and Richard Owen had revealed striking structural similarities between different animal groups, while embryologists noted that developing embryos of different species often appeared remarkably similar. These observations, combined with the growing recognition of Earth's antiquity, created fertile ground for new explanations of life's diversity and history. The pre-Darwinian period thus represents a crucial transition in scientific thought—a time when the accumulated weight of evidence was beginning to challenge traditional views, but a comprehensive explanatory framework had not yet emerged. These early naturalists, working without knowledge of genetics or the vast fossil record available today, nevertheless laid important groundwork for the revolutionary theory that would soon transform our understanding of life on Earth.

Chapter 2: Darwin's Revolution: The Origin of Natural Selection Theory

When Charles Darwin boarded HMS Beagle in December 1831 for what would become a five-year voyage around the world, he was a promising young naturalist but held conventional views about the fixity of species. The journey would transform both Darwin and ultimately the world of science. As he later wrote, "The voyage of the Beagle has been by far the most important event in my life and has determined my whole career." During this expedition, Darwin observed patterns in nature that would eventually lead him to his revolutionary theory. The Galapagos Islands proved particularly influential for Darwin's thinking. There, he observed finches with different beak shapes on different islands, each adapted to local food sources. He also noted that the islands' tortoises and mockingbirds varied from island to island in ways that corresponded to their environments. Initially, Darwin didn't fully grasp the significance of these variations, but after returning to England and consulting with ornithologist John Gould, he realized these were distinct but closely related species. This pattern suggested that species could change and diverge when isolated in different environments. The crucial insight that completed Darwin's theory came in October 1838 when, by his own account, he happened to read Thomas Malthus's "Essay on the Principle of Population." Malthus argued that human populations tend to grow faster than their food supply, leading to a struggle for existence. Darwin realized this principle applied to all species—more individuals are born than can possibly survive, creating competition for limited resources. In this struggle, individuals with advantageous traits would be more likely to survive and reproduce, passing those traits to their offspring. Over many generations, this process—which Darwin called "natural selection"—would lead to adaptation and the formation of new species. Despite formulating his theory by 1839, Darwin delayed publishing for almost twenty years, instead focusing on detailed studies of barnacles and other subjects while quietly amassing evidence for evolution. This delay ended dramatically in 1858 when Darwin received a manuscript from Alfred Russel Wallace, a naturalist working in the Malay Archipelago, outlining a theory remarkably similar to his own. This spurred Darwin to quickly prepare an abstract of his work, which was published in November 1859 as "On the Origin of Species by Means of Natural Selection." The publication of "Origin" triggered immediate controversy but also garnered significant scientific support. Darwin's theory differed from previous evolutionary ideas in several crucial ways: it proposed natural selection as the primary mechanism of change; it emphasized the gradual nature of evolution; it explained both adaptation and diversity; and it was supported by an overwhelming array of evidence from multiple fields. Thomas Henry Huxley, who became known as "Darwin's bulldog" for his fierce defense of the theory, reportedly remarked after first reading the book, "How extremely stupid not to have thought of that!" Darwin's theory revolutionized not just biology but human thought more broadly. By providing a natural explanation for the apparent design in living things, it challenged traditional religious interpretations of creation. By placing humans within the evolutionary process rather than separate from it, it transformed our understanding of humanity's place in nature. And by introducing the concept of historical contingency into biology, it replaced the idea of a static, divinely ordained natural order with a dynamic vision of life constantly changing through natural processes. Few scientific theories have had such profound and far-reaching implications for how we understand ourselves and the world around us.

Chapter 3: Anatomical Evidence: Vestiges and Rudimentary Structures

Among the most compelling lines of evidence for evolution are the vestiges and rudimentary structures found throughout the living world. These are anatomical features that appear to be remnants of structures that were functional in ancestral species but have been reduced or repurposed in descendants. Darwin devoted considerable attention to these structures, recognizing their powerful implications for his theory of descent with modification. The mammalian body contains numerous examples of such vestigial structures. The human appendix, a small pouch attached to the large intestine, is a reduced version of a larger structure used for digesting plant material in many other mammals. Whales possess small pelvic bones embedded in their musculature, despite having no hind limbs—clear remnants of their four-legged terrestrial ancestors. Male mammals, including humans, have nipples that serve no functional purpose but develop because all mammals share a common developmental pathway before sexual differentiation occurs. As Darwin noted, these structures make little sense if each species was independently created but are readily explained as inherited features from ancestors in which they were functional. Birds provide particularly striking examples of vestigial structures. Flightless birds like ostriches, emus, and kiwis possess reduced wings that cannot support flight. These species have lost the ability to fly but retain the basic wing structure inherited from flying ancestors. Similarly, many flightless insects on windswept oceanic islands have reduced or absent wings. Darwin observed this pattern on Madeira, noting that insects with full wings would likely be blown out to sea, making wing reduction advantageous in this environment. The pattern of wing reduction in multiple independent lineages on different islands provided compelling evidence for natural selection acting on inherited variation. The eyes of cave-dwelling animals offer another fascinating example of vestigial structures. Animals living in perpetual darkness, such as cave fish and certain salamanders, often possess reduced eyes covered by skin. These eyes develop during embryonic stages but degenerate as the animal matures. In some cases, closely related species show different degrees of eye reduction corresponding to how long their lineage has lived in caves. This pattern of gradual reduction over evolutionary time is precisely what Darwin's theory predicts—structures that no longer provide a survival advantage tend to diminish through natural selection or the accumulation of neutral mutations. Plant species also exhibit vestigial structures that reveal their evolutionary history. Many parasitic plants that no longer photosynthesize still produce reduced leaves or contain non-functional chlorophyll-related genes. Certain orchids possess structures that mimic the female forms of specific insect species to attract male pollinators, even in regions where those insect species are absent—suggesting these orchids evolved these structures in areas where the insects were present and then migrated to new regions. The distribution of vestigial structures across the tree of life follows patterns consistent with common descent. Related species tend to share similar vestigial features, with the degree of similarity corresponding to how recently they shared a common ancestor. This hierarchical pattern of vestigial traits, nested within taxonomic groups, provides strong evidence for Darwin's vision of life as a branching tree rather than a series of independently created forms. As he wrote in "Origin," these rudimentary structures tell the same story as other lines of evidence—that the natural world is the product of descent with modification through natural selection, not special creation.

Chapter 4: Geographic Isolation: Islands as Evolutionary Laboratories

Islands have served as natural laboratories for understanding evolution since Darwin's time, offering insights impossible to obtain from continental regions. Their isolation, limited size, and often unique conditions create evolutionary scenarios that reveal natural selection's power with exceptional clarity. Darwin himself was profoundly influenced by his observations on islands, particularly the Galapagos archipelago, where he encountered species found nowhere else yet clearly related to mainland forms. The most striking feature of oceanic islands is their high proportion of endemic species—organisms found nowhere else on Earth. The Hawaiian Islands, for instance, host over 1,000 endemic plant species that evolved from approximately 270 colonizing ancestors. Similarly, more than 90% of reptile species in the Galapagos are endemic. This pattern emerges because when organisms reach isolated islands, they encounter new environments with different selective pressures and few competitors. Natural selection then shapes these colonists into new forms adapted to local conditions. Over time, these island populations diverge so much from their mainland ancestors that they become distinct species, unable to interbreed even if they were to come into contact again. Archipelagos—groups of islands—reveal evolutionary patterns with particular clarity. In the Galapagos, Darwin observed that each island often hosted its own unique species of tortoise, mockingbird, and finch, yet these species were more similar to each other than to related species elsewhere in the world. This pattern, now called "adaptive radiation," occurs when a single ancestral species diversifies to fill multiple ecological niches. The most famous example is Darwin's finches (though Darwin himself didn't fully appreciate their significance during his visit), which evolved from a single ancestral species into at least 14 different species with beaks specialized for different food sources—from cracking seeds to probing flowers for nectar. Island species often evolve in surprising directions due to the absence of certain selective pressures. Without mammalian predators, birds on many islands have become flightless—like the dodo of Mauritius or the numerous flightless rails scattered across Pacific islands. Similarly, in the absence of large herbivores, plants on many islands have lost defensive thorns or toxic compounds. Conversely, some island plants have evolved "insular woodiness," becoming woody shrubs or trees despite being derived from herbaceous mainland ancestors. These patterns demonstrate how natural selection shapes organisms in response to local conditions, with traits being enhanced, reduced, or lost depending on their contribution to survival and reproduction in the specific island environment. The age of islands influences their evolutionary dynamics. The Hawaiian archipelago, formed by volcanic activity over millions of years, shows how evolution proceeds as islands age. The oldest islands, like Kauai, have the most endemic species and the most divergent forms, while the youngest island, Hawaii itself, has fewer unique species. This pattern occurs because older islands have provided more time for evolutionary divergence. Similarly, islands that have been isolated longer generally have more endemic species than those that were recently connected to continents. Islands continue to serve as evolutionary laboratories today, though human activities have dramatically altered many island ecosystems through introduced species, habitat destruction, and hunting. The vulnerability of island species to these changes—resulting in disproportionately high extinction rates—itself reflects their evolutionary history. Having evolved in isolation with few competitors or predators, many island species lack defenses against introduced threats. By studying both the remarkable adaptations of island species and their vulnerability to change, we gain crucial insights into evolutionary processes that apply throughout the living world.

Chapter 5: Extinction Events: Catalysts for Evolutionary Innovation

Throughout Earth's history, mass extinction events have repeatedly reshaped the trajectory of evolution, eliminating dominant groups and creating opportunities for survivors to diversify into vacant ecological niches. These biological crises, while devastating in their immediate impact, have served as powerful catalysts for evolutionary innovation, driving the emergence of new forms and contributing to the remarkable diversity of life we see today. The fossil record reveals at least five major mass extinction events over the past 500 million years, with the most severe—the Permian-Triassic extinction approximately 252 million years ago—eliminating an estimated 96% of marine species and 70% of terrestrial vertebrate species. This catastrophic event, likely caused by massive volcanic eruptions and subsequent climate change, effectively reset the evolutionary clock, creating ecological vacancies that survivors could exploit. In the aftermath, previously marginal groups like the archosaurs (ancestors of dinosaurs, birds, and crocodilians) and early mammal-like reptiles expanded into new niches, setting the stage for the Mesozoic Era. The most famous mass extinction, occurring at the Cretaceous-Paleogene boundary about 66 million years ago, eliminated non-avian dinosaurs along with approximately 75% of all species. This extinction, triggered by an asteroid impact combined with ongoing volcanic activity, created opportunities for mammals to diversify dramatically. Prior to this event, mammals had existed for over 150 million years but remained relatively small and ecologically restricted, living in the shadow of dinosaurs. After the extinction, mammals rapidly expanded into vacated niches, evolving into diverse forms including large herbivores, specialized carnivores, and eventually primates—ultimately leading to humans. This pattern illustrates how extinction events can fundamentally alter evolutionary trajectories, allowing previously suppressed groups to flourish. Extinction events don't just eliminate species; they change the rules of natural selection by altering environments and ecological relationships. During normal periods, competition between species is often the dominant selective pressure, favoring specialized adaptations for particular ecological niches. After mass extinctions, physical factors like temperature tolerance or dietary flexibility may become more important for survival. This shift in selective pressures explains why mass extinctions are often followed by the emergence of "disaster taxa"—generalist species that can thrive in disturbed environments. These opportunistic survivors then serve as the foundation for subsequent evolutionary radiations as ecosystems stabilize. The varying intensity and selectivity of different extinction events have shaped the overall pattern of life's history. Some extinctions disproportionately affected certain environments or taxonomic groups while sparing others. Marine organisms with calcium carbonate shells, for instance, are particularly vulnerable during ocean acidification events. This selective pressure has influenced which lineages persisted through time and which disappeared. The cumulative effect of these extinction filters has profoundly shaped modern biodiversity, determining which branches of the tree of life continued to diversify and which were pruned. While natural extinction events have occurred throughout Earth's history, human activities are now driving what many scientists consider a sixth mass extinction. Current extinction rates are estimated to be 100 to 1,000 times higher than background rates, primarily due to habitat destruction, pollution, overexploitation, and climate change. Unlike previous extinction events that created opportunities for evolutionary innovation over millions of years, the current crisis is occurring too rapidly for most species to adapt through natural selection. This unprecedented rate of change highlights the unique role humans now play in shaping evolutionary trajectories and the urgent need for conservation efforts to preserve Earth's biodiversity. The study of past extinction events provides crucial context for understanding evolution's long arc. These periodic crises reveal that life's history is not a steady march of progress but rather a complex journey shaped by both gradual adaptation during stable periods and rapid reorganization following catastrophes. The evolutionary innovations that emerged after each extinction remind us that life's remarkable resilience and creativity often flourish most dramatically in the aftermath of its greatest challenges.

Chapter 6: The Modern Synthesis: Genetics Validates Darwin's Vision

When Darwin published his theory of evolution by natural selection in 1859, he lacked a crucial piece of the puzzle: a viable theory of inheritance. Without understanding how traits were passed from parents to offspring, Darwin could not fully explain how beneficial variations persisted and spread through populations. This gap in knowledge represented a significant vulnerability in his theory, one that would be addressed through the emergence of genetics and its eventual integration with evolutionary theory in what became known as the Modern Synthesis. The foundation for this synthesis began with Gregor Mendel's experiments on pea plants in the 1860s, though his work remained largely unknown until 1900 when it was independently rediscovered by three scientists. Mendel's discoveries of discrete inherited factors (later called genes) and their patterns of transmission initially seemed at odds with Darwin's theory, which emphasized gradual change through the accumulation of small variations. Early geneticists like William Bateson emphasized mutations with large effects, leading some to question whether natural selection was the primary mechanism of evolutionary change. This period of tension between Darwinian and Mendelian approaches lasted for several decades. The reconciliation began in the 1920s and 1930s with the work of population geneticists who demonstrated mathematically that Mendelian inheritance was entirely compatible with gradual evolution through natural selection. R.A. Fisher, J.B.S. Haldane, and Sewall Wright developed mathematical models showing how beneficial alleles (gene variants) could increase in frequency within populations over generations, even with relatively small selective advantages. Their work demonstrated that natural selection operating on genetic variation could produce all the evolutionary patterns Darwin had described, providing the mechanism of inheritance that Darwin's theory had lacked. Field studies soon provided empirical support for these theoretical models. E.B. Ford's ecological genetics research in Britain demonstrated natural selection operating on visible genetic traits in wild populations of moths and butterflies. H.B.D. Kettlewell's famous studies of industrial melanism in peppered moths showed how environmental changes could drive rapid evolutionary responses, with dark-colored moths becoming predominant in polluted areas where they were better camouflaged against soot-darkened tree trunks. These and other studies confirmed that natural selection in the wild operated exactly as the mathematical models predicted. The Modern Synthesis expanded beyond population genetics to incorporate multiple biological disciplines. Ernst Mayr contributed crucial insights on speciation, explaining how new species form when populations become reproductively isolated. George Gaylord Simpson integrated paleontology, showing how the fossil record could be explained by the same evolutionary processes observed in living populations. Theodosius Dobzhansky's work on fruit fly genetics demonstrated the genetic basis of adaptation and reproductive isolation. Together, these scientists and others created a comprehensive framework that united Darwin's theory with genetics and extended it to explain all major evolutionary phenomena. The culmination of the Modern Synthesis is often associated with Julian Huxley's 1942 book "Evolution: The Modern Synthesis," which gave the movement its name. By this time, the integration of Darwinian selection with Mendelian genetics had created a robust theoretical framework that explained both microevolution (changes within species) and macroevolution (the origin of new species and higher taxa). This unified theory has since been further strengthened by molecular biology, which revealed the structure of DNA and the genetic code shared by all living organisms—providing the ultimate validation of Darwin's vision of common descent with modification. The Modern Synthesis represents one of science's greatest achievements—the integration of seemingly disparate fields into a coherent explanatory framework. It transformed Darwin's brilliant insight from a controversial theory into the central organizing principle of biology, supported by evidence from genetics, paleontology, biogeography, comparative anatomy, and eventually molecular biology. As Theodosius Dobzhansky famously wrote, "Nothing in biology makes sense except in the light of evolution"—a testament to how thoroughly the Modern Synthesis has shaped our understanding of the living world.

Chapter 7: Evolution's Impact: How Natural Selection Shapes Our World

The theory of evolution through natural selection has transformed our understanding of the living world far beyond the boundaries of academic biology. Its explanatory power extends from the microscopic realm of disease-causing organisms to the global patterns of biodiversity, providing insights that have practical implications for medicine, agriculture, conservation, and our broader understanding of humanity's place in nature. In medicine, evolutionary principles have become increasingly central to understanding disease and developing effective treatments. Bacterial evolution of antibiotic resistance represents natural selection in action—when antibiotics are present, bacteria with mutations conferring even slight resistance have a survival advantage and quickly become predominant in the population. This same process occurs with antiviral drugs and cancer treatments, as viruses evolve resistance and cancer cells adapt to chemotherapy. By applying evolutionary thinking, medical researchers have developed strategies like combination therapies and drug cycling to slow resistance evolution. Evolutionary medicine also helps explain why certain diseases exist at all—many conditions like diabetes and hypertension may result from mismatches between our bodies, adapted to ancestral environments, and modern lifestyles. Agriculture has been profoundly influenced by evolutionary principles, both historically through traditional breeding and in modern approaches. Humans have directed evolution through artificial selection for thousands of years, transforming wild ancestors into the crops and livestock that feed billions today. Modern plant and animal breeding explicitly applies evolutionary principles to develop varieties with desired traits. Meanwhile, agricultural pests and pathogens continuously evolve in response to our control methods—weeds develop herbicide resistance, insects evolve resistance to pesticides, and plant pathogens overcome bred resistance. Sustainable agriculture increasingly incorporates evolutionary thinking to develop strategies that work with rather than against evolutionary processes. Conservation biology is fundamentally shaped by evolutionary considerations. The preservation of genetic diversity within species has become a central conservation goal, as this diversity provides the raw material for adaptation to environmental changes. Conservation geneticists monitor the genetic health of small populations, recognizing that inbreeding can reduce fitness and adaptive potential. Evolutionary history also informs conservation priorities—unique evolutionary lineages with few close relatives represent irreplaceable branches of the tree of life. As climate change accelerates, conservation increasingly focuses on preserving species' evolutionary potential to adapt to changing conditions rather than simply maintaining current states. Perhaps most profoundly, evolutionary theory has transformed our understanding of humanity itself. By placing humans within the tree of life as one species among millions, evolution challenges traditional notions of human exceptionalism while providing a scientific framework for understanding both our uniqueness and our connections to other organisms. Human evolutionary studies reveal our species' African origins, our genetic relationship to other primates, and the evolutionary forces that shaped distinctive human traits like bipedalism, large brains, and complex language. This evolutionary perspective extends to human behavior and culture, with fields like evolutionary psychology and gene-culture coevolution exploring how natural selection has influenced human cognition, emotions, and social structures. The impact of evolutionary thinking extends beyond science into philosophy, ethics, and broader cultural understanding. By revealing the deep interconnectedness of all life through common descent, evolution provides a scientific basis for environmental ethics that recognizes our kinship with and responsibility toward other species. The evolutionary timeframe—spanning billions of years—gives perspective on humanity's brief existence and the long-term consequences of our actions. And the recognition that humans, like all species, are products of natural processes rather than special creation continues to influence religious and philosophical thought about human nature and purpose. As we face unprecedented global challenges like climate change, biodiversity loss, and emerging diseases, evolutionary principles become increasingly vital for developing effective responses. By understanding how species adapt to changing conditions, how ecosystems function through complex evolutionary relationships, and how our own evolutionary history shapes our capabilities and limitations, we gain essential insights for navigating an uncertain future. Darwin's revolutionary theory, refined and expanded through more than 160 years of research, remains our most powerful framework for understanding the living world and our place within it.

Summary

The story of evolution through natural selection represents one of humanity's greatest intellectual achievements—a theory that transformed our understanding of life from a static collection of divinely created forms to a dynamic, branching process driven by natural mechanisms. This journey from pre-Darwinian speculations to the modern synthesis reveals how scientific understanding itself evolves, with each generation building upon, refining, and sometimes revolutionizing the insights of those who came before. The evidence for evolution—from vestigial structures and geographical patterns to the fossil record and molecular genetics—has grown overwhelmingly stronger since Darwin's time, validating his core insight that all life is connected through descent with modification from common ancestors. Evolution's power lies not just in explaining life's history but in providing a framework for understanding our present and future. It illuminates why species are distributed as they are across the globe, why organisms carry the anatomical vestiges of their evolutionary past, how new diseases emerge, and why biodiversity responds as it does to environmental changes. For humanity, evolutionary theory offers both humbling perspective and empowering knowledge—we are one species among millions, products of the same natural processes that shaped all life, yet uniquely capable of understanding these processes and consciously influencing our own future evolution. As we face unprecedented global challenges, from climate change to emerging diseases, this evolutionary perspective becomes increasingly vital, reminding us of our deep interconnection with all living things and our responsibility to preserve the remarkable diversity produced by billions of years of evolution.

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Charles Darwin

Charles Robert Darwin of Britain revolutionized the study of biology with his theory, based on natural selection; his most famous works include On the Origin of Species (1859) and The Descent of Man (1871). Chiefly Asa Gray of America advocated his theories. Works of Jacques Martin Barzun include Darwin, Marx, Wagner (1941). Charles Robert Darwin, an eminent English collector and geologist, proposed and provided scientific evidence of common ancestors for all life over time through the process that he called. The scientific community and the public in his lifetime accepted the facts that occur and then in the 1930s widely came to see the primary explanation of the process that now forms modernity. In modified form, the foundational scientific discovery of Darwin provides a unifying logical explanation for the diversity of life. Darwin developed his interest in history and medicine at Edinburgh University and then theology at Cambridge. His five-year voyage on the Beagle established him as a geologist, whose observations and supported uniformitarian ideas of Charles Lyell, and publication of his journal made him as a popular author. Darwin collected wildlife and fossils on the voyage, but their geographical distribution puzzled him, who investigated the transmutation and conceived idea in 1838. He discussed his ideas but needed time for extensive research despite priority of geology. He wrote in 1858, when Alfred Russel Wallace sent him an essay, which described the same idea, prompting immediate joint publication. His book of 1859 commonly established the dominant scientific explanation of diversification in nature. He examined human sexuality in Selection in Relation to Sex , and The Expression of the Emotions in Man and Animals followed. A series of books published his research on plants, and he finally examined effect of earthworms on soil. A state funeral recognized Darwin in recognition of preeminence and only four other non-royal personages of the United Kingdom of the 19th century; people buried his body in Westminster abbey, close to those of John Herschel and Isaac Newton. Her fathered Francis Darwin, astronomer George Darwin, and politician, economist and eugenicist Leonard Darwin.(Arabic: تشارلز داروين)

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